var transparentImg = "img/transparent.gif";
function pngAlpha(obj){
	if(navigator.appVersion.indexOf("MSIE 5")!=-1 || navigator.appVersion.indexOf("MSIE 6")!=-1){
		var source = obj.src;
		if(obj && source.indexOf(transparentImg) == -1 && (obj.src.toLowerCase()).indexOf(".png") != -1){
			var ancho = obj.width;
			var alto = obj.height;
			obj.style.filter = "progid:DXImageTransform.Microsoft.AlphaImageLoader(src='"+obj.src+"')";
			obj.src = transparentImg;
			obj.width = ancho;
			obj.height = alto;
		}
	}
}